wp-includes/rest-api/class-wp-rest-server.php:1140Returns whether the REST server is currently dispatching / responding to a request.
bool public function is_dispatching() { return (bool) $this->dispatching_requests; }Introduced in 6.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/rest-api/class-wp-rest-server.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.